Memory formation requires de novo RNA and protein synthesis. Inhibition of mRNA and protein synthesis impairs memory formation in various behavioral task performances by rats. Such observations suggest that neural activities associated with learning lead to the expression of various genes encoding proteins that play important roles in memory formation (Davis and Squire (1984) Psychol. Bull. 96, 518–559; Matthies (1989) Annu. Rev. Psychol. 40, 381–404; and Lee, et al. (1992) Peptides 13, 927–937).
Extensive efforts have been made to identify genes specifically associated with certain forms of learning and memory. For example, by using two-dimensional gel analysis, several candidate proteins have been identified to be related to long-term sensitization of the gill-withdrawal reflex in Aplysia (Castellucci, et al. (1988) Neuron 1, 32 1–328). Approximately ten Drosophila genes have been found to be associated with olfactory learning and memory by screening of Drosophila mutants (Tully (1996) Proc. Nati. Acad. Sci. USA 93, 13460–13467). Further, by using a double-labeling method, proteins with increased glycosylation as a result of training have been identified in rats (Popov, et al. (1980) Neuroscience 5, 161–167).